Cooperative clinical investigation through pooling data from various institutions involved in prospective studies maximizes data accrual and patient benefit while decreasing individual patient risk. Information resulting from group efforts is more quickly obtained and subsequently more rapidly available to both other investigators and the physician in practice. Thus the goals of palliation and cure become more tangible. The stimulus of such a research effort is necessary for a meaningful program of peer and resident education. Clinical cancer chemotherapy is strongly committed to these ends and has evolved the cooperative group as the mechanism to achieve the goal. Mount Zion Hospital and Medical Center through its Medical Cancer Service has had a program of clinical drug investigation since 1967. It has recently sought and received funded affiliated status with the Western Cancer Study Group (WCSG). This union has resulted in increased physician participation in the WCSG as well as enlarging the patient study base of the group. Current expansion includes the full utilization of radiation therapy through the Claire Zellerbach Sarani Tumor Institute. Intragroup and intramural adjuvant studies are now under way. New program development evolving from Mount Zion Hospital personnel to enhance the WCSG research program has already occurred, while the Medical Cancer Service has concurrently acquired a more comprehensive group of studies in which to participate.